In general, a whole slide imaging (“WSI”) system can be an important tool for biomedical research and clinical diagnosis. In particular, advances of computer and image sensor technologies have accelerated the development of WSI systems for high-content screening, telemedicine, and digital pathology. An important aspect of WSI systems is to maintain the sample at the optimal focal position over a large field of view. In general, developing an auto-focus method for high-throughput WSI systems remains an active research area due to the potentials in industrial and clinical applications.
There are at least two general types of autofocus methods in WSI systems: 1) laser reflection based methods and 2) image contrast based methods. For laser reflection based methods, an infrared laser beam is reflected by the glass surface and creates a reference point to determine the distance between the glass surface and the objective lens. This method works well for a sample that has a fixed distance off the glass surface. If a sample varies its location from the surface, this method can fail to maintain the optical focal position. Different from the laser autofocusing method, the image contrast based methods generally track sample topography variations and identify the optimal focal position through image processing. This method acquires multiple images by moving the sample along the z direction and attempts to calculate the optimal focal position by maximizing a figure of merit of the acquired images. Typical figure of merits include image contrast, resolution, entropy and frequency content of the images. Since z-stacking increases the total scanning time, the image-based autofocus method can achieve improved imaging performance by trading off system throughput. However, due to the topographical variation of pathology slides, many commercially available WSI systems employ image contrast based methods for focus tracking.
A need exists among end-users and/or manufacturers to develop microscopy/imaging assemblies that include improved features/structures. In addition, a need remains for instruments, assemblies and methods that allow imaging techniques (e.g., microscopic imaging techniques) through designs and techniques that are easily understood and implemented.
Thus, an interest exists for improved microscopy/imaging assemblies and related methods of use. These and other inefficiencies and opportunities for improvement are addressed and/or overcome by the assemblies, systems and methods of the present disclosure.